Localization of Platelet-derived Growth Factor-stimulated Phosphorylation Cascade to Caveolae (*)
- From the Department of Cell Biology and Neuroscience, University of Texas Southwestern Medical Center, Dallas, Texas 75235
- § To whom correspondence should be addressed.
Abstract
Previously we showed that interleukin 1β stimulates the conversion of sphingomyelin to ceramide in the caveolae fraction of normal human fibroblasts. The ceramide, in turn, blocked platelet-derived growth factor (PDGF) stimulated DNA synthesis. We now present evidence that the PDGF receptor initiates signal transduction from caveolae. Cell fractionation and immunocytochemistry show caveolae to be the principal location of PDGF receptors at the cell surface. Multiple caveolae proteins acquire phosphotyrosine when PDGF binds to its receptor, but the hormone appears to have little effect on the tyrosine phosphorylation of non-caveolae membrane proteins. Five proteins known to interact with the phosphorylated receptor were found to be highly enriched in caveolae membrane. PDGF caused the concentration of three of these proteins to significantly increase in the caveolae fraction. Finally, PDGF stimulated the association of a 190-kDa phosphoprotein with the caveolae marker protein, caveolin. Therefore, ceramide may modulate PDGF receptor function directly in caveolae.
Footnotes
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↵* This work was supported by Grants GM 43169, GM 52016, and HL 20948 from the National Institutes of Health and a grant from the Perot Family Foundation. The costs of publication of this article were defrayed in part by the payment of page charges. This article must therefore by hereby marked “advertisement” in accordance with 18 U.S.C. Section 1734 solely to indicate this fact.
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↵1 The abbreviations used are:
- PDGF
-
platelet-derived growth factor
- PI 3-kinase
-
phosphatidylinositol 3-kinase
- IL-1β
-
interleukin 1β
- EGF
-
epidermal growth factor
- FGF
-
fibroblast growth factor
- MAP
-
mitogen-activated protein
- MAPK
-
MAP kinase
- PVDF
-
polyvinylidene difluoride
- PNS
-
postnuclear supernatant
- PM
-
plasma membrane
- CM
-
caveolae membrane
- NCM
-
non-caveolae membrane
- mAb
-
monoclonal antibody
- Ig
-
immunoglobulin.
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↵2 Mineo, C., James, G. L., Smart, E. J., and Anderson, R. G. W.(1996) J. Biol. Chem.271, in press.
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- Received December 13, 1995.
- Revision received January 29, 1996.
